movement off base would be severely restricted. afghan officials want 10,000 to 15,000 troops to stay for a decade at least. u.s. officials talk of 7,000 to 8,000. >> they're nervous about taking their first few steps without us. >> reporter: most afghan troops don't want americans to leave. >> we need strong support from international community, especially from u.s.. >> reporter: but why not just leave? the afghan government would likely collapse. afghanistan could again become a haven for terrorists. but after so many years would a force of 7,000 make a difference. iraq stands as a warning. there was no agreement there when the u.s. left. and the civil war has come back with a vengeance. afghans are gathering here in kabul this week to vote on the deal. if it passes, it will then be up to the united states to do it or not. richard engel, nbc news, kabul.